The employment of local soils for extraction of metallic elements was evaluated through batch tests to treat wastewaters generated in a petroleum refinery plant in southern Brazil. Clay and organic carbon content and clay mineralogy provide these soils, in principle, with moderate metal retention capacity. The following retention order was established: Cr3+ > Pb2+ > Cu2+ > Hg2+ > Cd2+, with total amount of metals retained varying from 36 to 65 meq kg-1. The results show the high efficiency of local soils for extracting metals from liquid effluents through sorption and precipitation processes under acid pH conditions.
retention test; metal pollution; wastewater treatment
